This invention relates to a process for the purification of gases contaminated by sulfuryl fluoride (SO.sub.2 F.sub.2). Gases of that type are formed, for example, in the production of sulfur hexafluoride or in the electrochemical fluorination of sulfur-containing compounds. The production of SF.sub.6 from the elements is accompanied, due to the presence of impurities in the starting materials, by the accumulation of a crude gas contaminated by SO.sub.2 F.sub.2 (see German Auslegeschrift No. 12 12 945 and No. 12 30 775). Such contaminated gas must be completely purified before the SF.sub.6 can be used for technical applications. The electrofluorination of sulphur-containing compounds is accompanied by the formation of an exhaust gas which, although largely hydrogen, also contains small fractions of SO.sub.2 F.sub.2 which must be eliminated before its release into the factory exhaust because sulfuryl fluoride can hydrolyse to form polluting compounds such as hydrofluoric and fluorosulfonic acid or hydrofluoric and sulfuric acid.
Although it undergoes measurable hydrolysis at 20.degree. C. (G. H. Cady and S. Misra, Inorg. Chem. 13 (4). 837-841 (1974)), sulfuryl fluoride reacts very slowly with water, particularly if it is heavily diluted with inert gases, such as sulfur hexafluoride (DE-AS Nos. 12 12 945 and 12 30 772). It is also known that alkaline hydrolysis does not yield fluoride and sulfate ions (equation 1), but rather fluorosulfate ions instead (cf. for example M. M. Jones and W. L. Lockhar, J. Inorg. Nucl. Chem. 30, 1237 (1968), equation 2): EQU SO.sub.2 F.sub.2 +4OH.sup.- .fwdarw.2F.sup.- +SO.sub.4.sup.2- +2H.sub.2 O (1) EQU SO.sub.2 F.sub.2 +2OH.sup.- .fwdarw.F.sup.- +SO.sub.3 F.sup.- H.sub.2 O (2)
Thus, in addition to fluoride, the fluorosulfate ion (which is much more difficult to precipitate) accumulates instead of the fluoride and sulfate ions, which would be easy to precipitate from water.
Accordingly, it has been proposed to absorb sulfuryl fluoride on solids, such as aluminium oxides, molecular sieves, hydroxides, oxides, carbonates and hydrogen carbonates of the elements of the 1st and 2nd Main Group of the periodic table, or on inert materials impregnated with oxides, hydroxides or carbonates of the 1st and 2nd Main Group of the periodic table, at temperatures in the range from -50.degree. C. to 350.degree. C. (See German Auslegeschrift Nos. 12 12 945 and 12 30 772). However, these processes are characterised by minimal utilization of the alkali available because sulfuryl fluoride only reacts on the solid surface offered to it with a shallow depth of penetration so that these processes are uneconomical, particularly when carried out continuously on a large scale.